Bumblebees are needed to pollinate the flowering crops and plants that living species need to survive. Even though bumblebees are basically in it for themselves when they forage for nectar (they need food to live), the plants they pollinate are absolutely dependent on bee pollination for their own survival.
There’s a direct correlation between the decline of a bumblebee species and a downward survival rate for the plants that particular species pollinates.
How to Identify Bumblebees?
There are over 255 species of bumblebees, and because so many of the different species appear similar to one another, it’s extremely challenging to identify one species from another.
The trait that is most easily recognized is “hair” colour, but since there are nearly 400 different combinations and patterns of the few common colours, an observer should be prepared to study other characteristics – like body size, face length (which typically corresponds to tongue size and how the bee gathers nectar), and the location of the ocelli (simple eye).
Geographic location may be another way to identify one species from another. But in some geographic regions, different species may be more difficult to tell apart because of something called Müllerian Mimicry. This type of colour and pattern mimicry typically occurs as a defence mechanism against predators.
If one species is aware of a neighbouring species that’s been able to protect itself using a deadly poison or stinger, the mimicking species can also protect itself by developing the same distinguishing features as the dangerous species. This is an evolutionary process that occurs over many generations, but there are certainly many examples of species that were able to successfully mimic their neighbours.
That’s why identification based only on colour and pattern is so difficult.
Because there are so many different species of bumblebees, universities and other organizations have developed field guides to identify species within a particular geographic region. There are guides on the internet for the bees nesting in each of the fifty states, the broad regions of the Eastern and Western U.S., the territories of Canada, the U.K, and the many other locations where bumblebees have habitats.
Glancing at a page in one of these guides, there is – for each species – a description of food sources, tongue (proboscis) length, head size, and which other species it resembles. There are also diagrams that identify the physical appearance of queens, males, and (female) workers.
Where Can Bumblebees Be Found?
Bumblebee habitats can be found in nearly every region of the world, but they are least prevalent in Africa and parts of India. Also, bumblebees were not native to Australia and New Zealand until they were introduced to help with pollination. Bumblebees adapt well in temperate climates and don’t mind the cold. They are also present in alpine environments.
China is the country that is home to about half of the bumblebee species (124 out of a total of 255 different species). There are about 49 different species in the United States, 24 in the UK, 68 across Europe, and 24 in South America.
How Are Bumblebees Different From Other Bee Species?
There are 20,000 species of bees. Bumblebees belong to the genus Bombus and the family Apidae. Other bees within the Apidae family include honey bees, carpenter bees, cuckoo bees, digger bees, stingless bees, and orchid bees.
Honey Bees vs Bumblebees
Bumblebees are much larger than honey bees, have a more rounded abdomen, dark wings, and a lot more hair. Honey bees’ wings are translucent and their abdomens are more pointy.
Honey bees and bumblebees also differ in the types of plants they prefer to pollinate, and that’s partly because honey bees are more likely found among human populations, while bumblebees live in nests in the wild.
Honey bees like sugary foods, they can often be seen near garbage cans that contain soda cans and candy wrappers. They pollinate nearly 80% of fruits, vegetables, and ornamental plants. Bumblebees, in contrast, pollinate the plants found in prairie lands.
Bumblebees also differ from honey bees in the way they make honey. While honey bees mix nectar with a stomach enzyme to start honey production and then place it in a wax cell where they let it evaporate, bumblebees don’t go to all of that trouble.
They just collect nectar and keep it in a cup-like contraption that they build. It’s not dehydrated. Bumblebees use this nectar to survive during their short lifecycle.
Bumblebees are also less social than honey bees. Several thousand bees make up a honey bee colony, while a bumblebee colony typically maxes out around 400, and can include as few as only 40 bumblebees.
When it comes to stinging, bumblebees are more protected than honey bees. A bumblebee can sting several times and not lose its stinger. Contrast that to a honey bee, which can sting only once. It’s just the one time because the stinger gets caught, and when the honey bee tries to get away, the stinger gets ripped out and the honey bee dies.
Are Bumblebees Endangered?
As recently as February 2020, Science published research showing the dramatic drop in bumblebee survival rates between 1975 and 2000. During this period of time, North American bumblebee survival rates fell by about 46 per cent!
One of three bumblebee species is in decline in North America, and in 2017, the Rusty Patched Bumblebee (Bombus affinis) was the first bee in the continental U.S to be labelled an endangered species.
The dropoff in survival rate is believed to be the result of many causes, including habitat loss, pathogens, pesticides, and climate change. Climate change often gets the most press, while factors like agricultural methods and the introduction of exotic bumblebee species for pollination get little attention.
Two other species on the brink of extinction are Bombus franklini (in southern Oregon and northern California) and Bombus occidentalis (in the western U.S and Canada). In the Northwest Territories of Canada, Bombus occidentalis mckayi (a subspecies of Bombus occidentalis), Bombus terricola, and Bombus bohemicus are declining, and in Europe, 24% of bumblebee species are endangered.
Even though about half of the bumblebee species are in East Asia, it’s only recently that the region has begun to study its bee populations and examine issues related to survival. It is now thought that 10-17% of the East Asian bumblebee species will be endangered by 2050.
What Is the Role of the Queen Bumblebee?
A new bumblebee colony forms every year, and it is the queen that emerges from hibernation after a long winter ready to get strong, find a new nest, and lay her eggs.
She hasn’t eaten all winter, so she must find food and regain strength to locate a suitable home. When she finds the perfect place, she’ll lay her eggs and protect them in a ball of pollen and self-produced wax.
When the eggs hatch, the grubs remain inside the ball of pollen and wax until they are developed enough to become either worker bees (through fertilization by other worker bees) or male drones (that are not fertilized).
Once in the nest, the queen’s job is to continue to reproduce, while the worker bees take on the role of nest construction and pollen/nectar collection. Meanwhile, the queen tries to assert her dominance as the only bee capable of reproducing, and she does so by secreting a hormone that suppresses the development of ovaries in the worker bees.
The worker bees who are able to avoid this suppression go on to become the next generation of queen bees who will fly off to another nest to find a drone to mate with. All of the bees within the colony will die after the summer except the new queens, who feed heavily and then hibernate underground. The queens who survive will begin the process anew in the early Spring.
What Do Bumblebees Eat?
The bumblebee diet is very simple, as bumblebee food consists only of nectar and pollen. Nectar provides energy and pollen provides protein.
Bumblebees differ from honey bees in the amount of food they store. Since honey bees have a much longer lifecycle, they must have enough food to last throughout the long winter when they won’t be able to forage. Bumblebees, however, gather only what they need in the short term.
They are not going to expend their energy collecting nectar and converting it into honey because they don’t need to store it for the long haul. They simply place the nectar in a “cup” so they can access it when they need it.
Bumblebee Foraging Behaviour
Bumblebee foraging behaviour is extremely complex, and scientists haven’t yet established definitive conclusions.
For example, available data hasn’t been able to conclusively state how far bumblebees fly to forage for food, and it seems to vary based on species. Some studies have found that smaller colonies travel less than larger ones to collect pollen and nectar.
Some evidence suggests that bumblebees learn which flower species offer the most pollen and nectar and then continue to visit those flowers. There are particular flowers that pose challenges for bees because their tongues aren’t long enough to reach the nectar source. Once they figure out how to get to the nectar, they tend to make good on their experience and return to these same flower species.
Bumblebees will also notice which flowers are “popular” and conclude that they may be able to be rewarded if they forage there. But they will avoid flowers that were recently visited by other bumblebees. They can detect which flowers were already foraged using scent markers excreted by the bee that visited the flower. Scent marking conserves energy that may have been wasted on a flower that has already been pollinated.
Because bumblebees are well adapted to cold weather, they’re often active in late winter and in early fall. It’s especially important for the queen to be able to forage early in the season after the period of hibernation has ended. She’ll need to find food quickly and readily so that she has the energy to establish a nest and provide for her brood.
Which Flowers Attract Bumblebees?
Like other bees, bumblebees are attracted to colours and smells when deciding where to forage. Their favourite colours appear to be purple, blue, and yellow. But they’re also looking for flowers and plants where nectar can be obtained easily, which depends a lot on the bees’ anatomy.
That means those with shorter tongues are looking for flowers that are short and open (like daisies and allium), while those with longer tongues can find a good supply of nectar in deeper flowers, such as honeysuckle.
Here are some of the bumblebees’ favourite flowers:
| Bugle | Catmint |
|---|---|
| Chives | Clover |
| Comfrey | Foxglove |
| Geranium | Heather |
| Larkspur | Lavender |
| Marjoram | Nasturtium |
| Rosemary | Sage |
| Snapdragon | Thistle |
Are Bumblebees Aggressive?
Unlike honey bees, bumblebees can sting multiple times. That is because their stingers are smooth and don’t get ripped from their abdomen when the victim of the sting attempts to detach from the stinger.
But bumblebees are much less defensive than honeybees and sting only when their nests are disturbed. And since bumblebee colonies are much smaller than honey bee colonies, there will be fewer bees to contend with if they swarm after a disturbance.
Some say that a bumblebee sting hurts less than a honey bee or wasp sting, and bumblebees will not leave behind a venom sac when it stings (honey bees do this). But a bumblebee sting can be very dangerous if someone gets stung on their head or neck because it could cause wheezing and breathing difficulty. And if they are allergic to the venom, the sting could be life-threatening.
Male bumblebees (drones) cannot sting; only the queen and the female workers have that capability. The queen usually saves her stings for rival queens.
How to Deter Bumblebees?
Generally, bumblebees don’t mean any harm. But if someone wants to keep away from them, here are some ways to do so:
- Most insects hate peppermint and anything spicy like cinnamon. Include a few drops of these essential oils with water and a couple of teaspoons of liquid dish soap in a spray bottle, and then direct the spray to the area of the bees. They will disperse.
- Citrus and eucalyptus oil are also good repellents.
- Water your garden frequently because bumblebees prefer to build their nests near dry, sandy soil.
- Trick the bees by filling a bowl or cup with a sugary liquid and then place it a few yards from where you’re gathering.
- Avoid wearing bright colours and floral prints.
